Valve-gear for internal-combustion engines.



J; A. PRESTWIGH.

VALVE GEAR FOB. INTERNAL COMBUSTION ENGINES.

APPLICATION FILED DEO.31, 1912.

Patented Sept. 16

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/VVE/V70 J. A. PRESTWIGH. VALVE GEAR POE INTERNAL COMBUSTION ENGINES.

APPLICATION FILED DEC. 31, 1912.

1,073,284, Patented Sept. 16, 1913.

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1 COLUMBIA PLANDGRAFH CO, WASHINGTON, D. C.

JOHN ALFRED PRESTWICH, OF TOTTENHAM, LONDON, ENGLAND.

VALVE-GEAR FOE INTERN AL-COMBUS'IION' ENGINES.

Specification of Letters Patent.

Patented Sept. 1c, 1913.

Application filed December 31, 1912. Serial No. 739,480.

To all whom, it may concern:

Be it known that I, J OHN ALFRED Pansr- WIOH, of Northumberland Park, Tottenham, London, England, engineer, am in possession of an invention for Improvements in or Relating to Valve-Gear for Internal- Combustion Engines, of which the following is a specification.

This invention relates to valve gear for internal combustion engines and has for its object to provide an improved and simplified construction of gear therefor.

The invention is particularly applicable to two cylinder V-type engines where the cylinders are disposed on the upper side of a crank case and the invention will be described as applied tosuch an engine, though it is to be understood that the gear can be applied to other types of engine where the arrangement of the cylinders permits.

According to this invention as applied to a V-type engine having two cylinders disposed at diiferentangles a single cam shaft carrying one exhaust and one inlet cam is adapted to operate the valves or valve spindles through the medium of pivotally mounted tappet or intermediate levers arranged in pairs in the manner of a pair of calipers or equivalently each pair of levers consisting of the inlet valve lever of one cylinder and the exhaust valve lever of the other cylinder, said levers engaging the cam shaft on diametricallyopposite sides of the shaft or substantially so or at diiferent radial positions according to the angular positions of the valve spindles and cylinders.

With the above described mechanism may be combined means for independently operating the exhaust levers to relieve the compression so as to reduce the same to that actually required, and such means may consist of any suitable device for spreading the exhaust levers apart, and for the same purpose the cam shaft may be fitted with a movable cam face adapted to be protruded into the path of the exhaust levers as the cam shaft rot-ates during the running of the engine, thereby relieving the compression at half stroke or during any required portion of the stroke. The respective levers are adapted to engage and operate the valve spindles by suitable lumps or projections thereon. The whole gear is conveniently mclosed in a casing upon the face of the crank case.

The accompanying drawings show one construction of the improved gear.

Figure 1 is an elevation with the cover of the gear case removed. Fig. 2 is a vertical section of Fig. 1.

a is the cam shaft driven from the crank shaft 1).

0 is the cam for operating the inlet valves, and d is the cam for operating the exhaust valves.

0 e are the two inlet valve levers having shoulders e e for operating the inlet valve spindles f f.

g g are the exhaust cam levers which operate the exhaustvalve spindles li 7t. These levers g g are of T-shaped form, one arm of the T bearing upon the operating cam and the other arm bearing upon the end of the valve spindle. The valve levers are pivoted upon two centers 71 2', each pivot carrying a pair of levers consisting of the exhaust lever of one engine and the inlet valve lever of the other engine; the two inlet levers are crossed over one another so as toengage the cam on opposite sides of the cam shaft (1.

In operation as the cam shaft rotates, the inlet cam 0 first engages and oerates the lever e and then the lever e of tie two cylinders respectively and in like manner the cam (Z operates first the exhaust lever g and then the lever g.

In order that the compression may be relieved at a suitable point in the stroke when required, there is mounted on the cam shaft a pivoted lever j pivoted at y" at one end, and having at its other end an enlarged cam head 7' which runs around the face of a normally stationary but adjustable cam 70 having flat sides or recesses is normally disposed opposite the ends of the exhaust levers, the arrangement being such that the pivoted lever j normally lies close against the cam 70 and its head j travels across the recess or flat face 70 without engaging with the exhaust levers, while by adjusting the position'of the cam 70 which is mounted on a rotary sleeve the recess 70 is moved out of position and the head j in passing over the projecting portion is of the cam 76 when next to the levers g 9 projects so far out as to engage and operate the exhaust levers thereby opening the exhaust valve and re lieving the compression. The cam 76 is conveniently mounted on a sleeve 70 the end of which terminates in a toothed wheel 70 operated by another toothed wheel m rotated by means of a cord or Bowden wire by the driver. If required the cam is may be adjusted by other suitable mechanism.

In order that the exhaust valve may be released or opened by hand independently of the cam 79 another cam spindle 0 is provided disposed above the cam shaft (0 and between same and the pivots a a, the said cam shaft carries an oblong cam which normally lies in inoperative position between two horns or project-ions upon the exhaust levers. In use the cam shaft is rotated by an external wheel or handle by which the cam 0 is rotated so as to spread apart the horns and open the exhaust valves. A spring 0 is provided for returning the cam 0 to normal position.

hat I claim as my invention and desire to secure by Letters Patent is 1. The improved valve operating gear for the valves of two engine cylinders disposed radially, comprising a Single cam shaft carrying one exhaust and one inlet cam, and adapted to operate the valves or valve spindles through the medium of pivotally mounted tappets or intermediate levers arranged in pairs, each pair of intermediate levers'consisting of the inlet valve of one cylinder and the exhaust valve lever of the adjacent cylinder, said levers engaging the cams on approximately diametrically opposite sides of the cam shaft at different radial positions according to the angular positions of the valve spindles or cylinders.

2. The improved valve'operating gear consisting of the combination with two engine cylinders arranged in V form of a single cam shaft carrying one inlet cam and one exhaust cam and pairs of valve tappet levers pivotally mounted in pairs consisting of the inlet valve lever of one cylinder and the exhaust valve lever of the other cylinder, said pair of levers engaging the cam shaft on approximately diametrically opposite sides.

8. The improved valve gear comprising the combination with the valve spindles of two cylinders arranged V fashion of a single cam shaft carrying one exhaust and one inlet cam, two inlet valve levers pivoted on adjacent centers within the angle between the axes of the cylinders, said levers crossing one over the other to engage the cams on opposite sides of the cam shaft, two exhaust levers pivoted on the same centers as the inlet levers, said exhaust levers being of T shape, the arm of the T engaging the cam at one end and the valve spindle at the other.

4. The improved valve operating gear for the valves of two engine cylinders disposed radially, comprising a single cam shaft carrying one exhaust and one inlet cam, and adapted to operate the valves or valve spindles through the medium of pivotally mounted tappets or intermediate levers arranged in pairs, each pair of intermediate levers consisting of the inlet valve of one cylinder and the exhaustvalvelever of the adjacent cylinder, said levers. engaging the cams on approximately diametrically opposite sides of the cam shaft at different radial positions according to the angular positions of the valve spindles or cylinders, an ad justable cam device rotating coaxially'with the cam shaft and adapted to be protruded into the path of the exhaust levers during the compression stroke for the purpose set forth. '7

5. The improved valve operating gear consistingof the combination with two engine cylinders arranged in V form of a single cam shaft carrying one inlet cam and one exhaust cam and pairs of valve tappet levers pivotally mounted in pairs consisting of the inlet valve lever of one cylinder and the exhaust valve lever of the other cylinder, said pair of levers engaging the cam shaft on approximately diametrically opposite sides, an adjustable cam device rotating coaxially with the cam shaft and adapted to be protruded into the path of the exhaust levers duringthe compression stroke for the purpose set forth.

6. The improved valve gear comprising the combination with the valve spindles of two cylinders arranged V fashion of a single cam shaft carrying one exhaust and one inlet cam, two inlet valve levers pivoted on adjacent centers within the angle between'the axes of the cylinders,said levers crossing one over the other to engage'the cams on opposite sides of the cam shaft, two exhaust levers pivoted 0n the same centers as the inlet levers, said exhaust levers being of T shape, the arm of the T engaging the cam at one end and the valve spindle at the other, an adjustable cam device rotating coaxially with the cam shaft and adapted to be protruded into the path of the exhaust, levers during the compression stroke for the purpose set forth. i

7. The combination with two exhaust levers pivoted on adjacent centers and having their free ends engaging cams on a single cam shaft, ofan adjustable cam device rotating coaxially with the cam shaft and adapt ed to be protruded into the path of the exhaust levers during the compression stroke for the purpose set forth. r

8. The improved valve operating gear for the valves of two engine cylinders disposed radially, comprising a single cam shaft carrying one exhaust and one inlet cam, and adapted to operate the valves or valve spindles through the medium of pivotally mounted tappets or intermediate levers arranged in pairs, each pair of intermediate levers consisting of the inlet valve of one cylinder and the exhaust valve lever of the adjacent cylinder, said levers engaging the cams on approximately diametrically opposite sides of the cam shaft at different radial positions according to the angular positions of the valve spindles or cylinders, and an adjustable cam coaxial with the cam shaft, a radially movable cam head running around the face of said adjustable cam, and adapted to be protruded or withdrawn by the adjustment of said cam for the purpose of operating the exhaust cam levers and releasing the compression as required;

9. The improved valve operating gear consisting of the combination with two engine cylinders arranged in V form of a single cam shaft carrying one inlet cam and one exhaust cam and pairs of valve tappet levers pivotally mounted in pairs consisting of the inlet'valve lever of one cylinder and the exhaust valve lever. of the other cylinder, said pair of levers engaging the cam shaft on approximately diametrically opposite sides, and an adjustable cam coaxial with the cam shaft, a radially movable cam head running around the face of said adjustable cam, and adapted to be protruded or withdrawn by the adjustment of said cam for the purpose of operating the exhaust cam levers and releasing the compression as required.

10. The improved valve gear comprising the combination with the valve spindles of two cylinders arranged V fashionof a single cam shaft carrying one exhaust and one in let cam, two inlet valve levers pivoted on adjacent centers within the angle between the axes of the cylinders, said levers crossing one over the other to engage the cams on opposite sides of the cam shaft, two exhaust levers pivoted on the same centers as the inlet levers, said exhaust levers being of T shape, the arm of the T engaging the cam at one end and the valve spindle at the other, and an adjustable cam coaxial with the cam shaft, a radially movable cam head running around the face of said adjustable cam, and adapted to be protruded or withdrawn by the adjustment of said cam for the purpose of operating the exhaust cam levers and re leasing the compression as required.

1.1. The improved valve operating gear for the valves of two engine cylinders disposed radially, comprising a single cam shaft carrying one exhaust and one inlet cam, and adapted to operate the valves or valve spindles through the medium of pivotally mounted tappets or intermediate leers arranged in pairs, each pair of intermediate levers consisting of the inlet valve of one cylinder and the exhaust valve lever of the adjacent cylinder, said levers engaging the cams at different radial positions according to the angular positions of the valve spindles or cylinders.

In testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses.

O. J. VVoR'rH.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents, Washington, D. G. 

